Biotech Investment

Lightspeed joins $130m oversubscribed series B in US biotech Protego

• ByStartupStory     |    December 2, 2025

Lightspeed Venture Partners has joined a heavily oversubscribed $130 million Series B round in US-based Protego Biopharma, a clinical-stage biotech developing first-in-class small molecule drugs that “reprogram” protein folding to treat systemic amyloid diseases such as AL amyloidosis.

The Series B is led by Novartis Venture Fund and Forbion, with new investors Omega Funds, Droia Ventures, YK Bioventures, and Digitalis Ventures joining as fresh backers. Existing investors — including Vida Ventures, MPM BioImpact, Lightspeed Venture Partners, and Scripps Research — all participated, signalling strong insider conviction in Protego’s platform and lead asset.

Funding will advance Protego’s lead candidate PROT-001, an oral small molecule “pharmacological chaperone,” into a pivotal clinical trial for AL amyloidosis, a rare and often fatal protein misfolding disorder that causes toxic light-chain deposits in organs, especially the heart. PROT-001 is designed to bind a cryptic site on misfolded light chains, stabilize them, and restore a structure the body can safely clear, aiming to deliver the first truly disease-modifying therapy for this indication rather than just managing symptoms.

Protego’s platform targets the root cause of systemic amyloid diseases by correcting misfolded proteins upstream, a strategy investors say differentiates it from antibody drugs that attempt to clear existing deposits and have seen mixed late-stage results. With Phase 1 underway and pivotal testing planned after initial readouts, the company will use the new capital for trial execution, biomarker work, and pipeline expansion into additional protein misfolding disorders.

Executive chairman Ed Hurwitz and acting chief business officer Chris Weyrer from Vida Ventures are closely involved as Protego scales for late-stage development. The round underscores continuing appetite for high-conviction rare-disease plays even in a selective biotech funding environment, especially where mechanistic rationale and unmet need are both strong.

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